Condensing apparatus for refrigeration equipment



Feb. 15, 1966 c. E. WHITE 3,234,751

CONDENSING APPARATUS FOR REFRIGERATION EQUIPMENT Filed Aug. 15, 1963 2 Sheets-Sheet 1 6 Z6 :52 INVENTOR.

Feb. 15, 1966 c. E. WHITE 3,234,751

CONDENSING APPARATUS FOR REFRIGERATION EQUIPMENT Filed Aug. 13, 1965 2 Sheets-Sheet 2 l J W'- rae 7a FU/VP HEAWNG COIL United States Patent 3,234,751 CONDENSIN G APPARATUS FOR REFRIGERATION EQUIPMENT Clarence E. White, Gurnee, ill; Elizabeth C. White, administratrix of said Clarence E. White, deceased Filed Aug. 13, 1963, Ser. No. 301,716 16 Claims. ((31. 62-183) This invention relates to refrigeration systems, and more particularly to improved condensing apparatus associated with such systems.

The function of condensing apparatus in a refrigeration system is to cool the refrigerant, preferably to its liquid state, after it has been compressed. Water is normally used as a cooling fluid within the condenser, and the heat taken up from the refrigerant by the cooling fluid, is expelled by pumping the water through a water tower or the like, whereby some of the water is evaporated in order to reduce the temperature of the Water. In the water tower, air is forced through the cooling water in order to evaporate part of it, and the water becomes laden with air-borne dirt and grime which settles out Within the con denser, thereby reducing its heat-transfer efliicency, and restricting flow therethrough. Accordingly, the condenser must be periodically cleaned, in order to maintain it at its peak efiiciency.

Prior art condenser apparatus has been very difiicult to clean, it being necessary to dismantle a large part of the apparatus, and scrub the inside of the conduit for the cooling fluid. This is an expensive and time consuming process. Moreover, the design of prior art condensing apparatus has been such as to promote the deposition of dirt within the condenser where it does the most harm, by providing for a relatively smooth flow of cooling fluid therein.

Accordingly, it is a principal object of the present invention to provide improved condensing apparatus, which may be simply and economically cleaned.

Another object of the present invention is to provide improved condensing apparatus which may be cleaned without the necessity of dismantling any part of it.

Another object of the present invention is to provide means for removing heat from a refrigerant flowing within a condenser by creating turbulence in the cooling fluid within the condenser.

A further object of the present invention is to provide an improved condenser apparatus which is both simple in construction and easy to maintain.

Another object of the present invention is to provide condensing apparatus including a reservoir of cooling fluid for removing heat from the refrigerant, and means for preventing the fluid in such reservoir from stratifying into different temperature layers.

Another object of the present invention is to provide an improved refrigerant receiver tank associated with the condenser.

Another object of the present invention is to provide condenser apparatus including means for causing dirt to settle out within the condenser other than on the conduit containing the refrigerant.

A further object of the present invention is to provide a reservoir of cooling fluid for operating one or more condensers, a reservoir which recaptures substantially all of the heat removed from the refrigeration apparatus during the operation of refrigeration apparatus, and returns the heat when the refrigeration apparatus is defrosted.

These and other objects and advantages of the present invention will become manifest upon an examination of this specification, and the accompanying claims and drawmgs.

3,234,751 Patented Feb. 15, 1966 In one embodiment of the present invention, there is provided improved condensing apparatus including a reservoir of cooling fluid, refrigerant containing conduit means disposed in the reservoir, means for recirculating fluid within the reservoir past the conduit means, and means for creating turbulence within said cooling fluid in the vicinity of the conduit means.

Reference will now be made to the accompanying drawings in which:

FIG. 1 is a perspective view of a portion of a refrigeration system embodying the present invention;

FIG. 2 is a side elevation, partly in section, of a portion of the apparatus illustrated in FIG. 1;

FIG. 3 is a plan view, partly in section, of the apparatus illustrated in FIGS. 1 and 2;

FIG. 4 is an enlarged vertical cross-sectional view of one of the condenser-receivers of FIGS. 2 and 3; and

FIG. 5 is a functional block diagram of a refrigeration system in which the present invention may be used.

Referring now to the drawings, there is shown in FIG. 1 a tank 10 for containing a quantity of water which is used as a cooling fluid in the operation of the condenser to cool the refrigerant flowing through the condenser. The tank 10, hereinafter sometimes referred to as the cooling tank, is closed on five sides but is open at the top, and an angle member 12 surrounds the periphery of the top opening of the tank. The tank 10 is supported in elevated position by a number of legs 14, and cross members 16 secured to the legs 14. A cover 18 is provided on the front of the cooling tank 10 to house the electrical control equipment associated with the operation of the refrigeration system, and is preferably hinged to permit easy opening of the cover for inspection of the controls. A shelf 20 is secured to the legs 14, and supports a number i of compressor units 22. Each of the compressor units 22 is provided for a separate refrigeration unit or units, and has its own supply of refrigerant. Each of the compressors 22 is provided with an associated condenser-receiver within the tank 10, all of the condenser-receivers in the tank 10 sharing the same cooling fluid.

Each of the condenser-receivers includes a cup-shaped member 24 which rests on the bottom of the floor 26 of the tank 10. A cylindrical receiver tank 32 is disposed within the cup-shaped member 24, and has its bottom wall spaced from the bottom Wall of the cup-shaped member by legs 34. The cup-shaped member 24 preferably has the configuration of a right circular cylinder, and is preferably formed of a plastic material. The receiver tank 32 also preferably has the configuration of a right circular cylinder and is preferably formed of copper, or some other material having good heat conducting properties.

An outside coil 27 in the form of a helix of tubing or conduit surrounds the cup-shaped member 24, and has its upper end connected to a tube 28, and its lower end connected to a tube 30. The tube 30 is connected to the interior of the receiver tank 32. An inside coil 36 is also provided in the form of a helix adjacent the inside wall of the cup-shaped member 24, and has its upper end connected to a tube 38 and its lower end connected to a tube 40. The tube 40 is also connected to the interior of the receiver tank 32. Each of the coils 27 and 36 is preferably formed of copper for the purpose of good heat conduction, and is preferably wound rather loosely to permit water to flow easily between the convolutions of each coil. This tends to increase the turbulence of the water flow, which is desirable for reasons to be discussed more particularly hereinafter. The coils are also preferably spaced from the inside and outside surfaces of the cup-shaped member 24, also to promote turbulence, by brackets (not shown) attached to the cup-shaped member 24.

Both of the tubes 28 and 33 are connected to the outlet of a compressor, and refrigerant is caused to flow downwardly through the coils 27 and 36 and then into the top of the receiver tank 32. Refrigerant is withdrawn from the receiver tank via a tube 42 communicating with the interior of the receiver tank and opening near the bottom of the tank 32. Thus the coldest refrigerant within the receiver tank is Withdrawn through the tube 42.

Within the cooling tank 10, water is continuously recirculated by means of a pump 44 which draws water through an intake line 46 and forces it into a line 48. A plurality of feeder tubes 50 connect the line 48 to each condenser-receiver at the bottom of the space between the receiver tank 32 and the cup-shaped member 24, in a manner which is substantially axially symmetric with the receiver tank 32. Water is thereby forced to flow through the tube 50 downwardly into the space between the receiver tank 32 and the cup-shaped member 24, and then upwardly past the inner coil 36. When the water reaches the top of the cup-shaped member 24, it spills over the edge of the cup-shaped member in every direction and flows down over the surface of the outer coil 27 until it reaches the fluid level within the cooling tank it). The rate at which water is pumped through the feeder t depends, naturally, upon the size of the condensenreceiver unit. It has been found that a rate of flow of approximately three gallons per minute, per ton of refrigeration, is satisfactory. The rate of water flow is sufficiently high to cause the flow to be somewhat turbulent as it flows past the inner coil 36. The water flow is also turbulent as it passes downwardly over the outer coil 27. The turbulence of the water as it flows past the coils 2'7 and 36 causes the heat extracted from the coils to be substantially uniformly distributed over the cross-section of the flow, thereby achieving increased efficiency by avoiding temperature strata within the flow.

In addition, the turbulent flow continually washes the outer surfaces of the coils 27 and 36 and prevents dirt within the water from lodging on these coils. Near the inner and outer surfaces of cup-shaped member 24, however, the water moves at a slower velocity, because it is there flowing over surfaces generally parallel with the direction of flow, and there is therefore less resistance of the deposition of dirt on the walls of the cup-shaped member 24. However, as the surface of the cup-shaped member 24 is not a heat exchanging surface, the dirt deposited here does not result in a decrease in efficiency of the condenser unit.

The cup-shaped member 24- is preferably constructed of fiberglass, impregnated with a synthetic resin. This material has been found to he eminently suitable for use as a dirt collector, since the dirt within the water appears to have an afiinity for such material and therefore readily deposits out on the surface of the cup-shaped member 24.

It should be noted that any dirt which is deposited on the Walls of the cup-shaped member 24, is relatively easy to clean out, it being only necessary to reach between the wall of the cup-shaped member 24 and one of the coils to dislodge the dirt with a brush or the like, whereupon the dirt is carried over the lip of the cup-shaped member 24 into the cooling tank Where it may be drained. The open top of the cooling tank 10 also promotes ease of cleaning of the condenser coils, as no part of the apparatus must be disassembled for the cleaning operation.

The level of water is maintained within the cooling tank 10 at a predetermined level by the cooperation of a standpipe 52 which prevents the Water level from rising too high, and a float actuated inlet valve 54 which prevents the water within the tank 10 from becoming too low. The water level is maintained part way down the outside of the outer coil, so that the free falling water falls only over the top portion of the outer coil. The selection of the water level within the tank 10 is largely a compromise between the desirability of having as many as possible convolutions of the outer coil above the water level, where it is subject to turbulent flow, and the necessity for providing at least a minimum volume of water within the cooling tank 10 so that heat may be readily absorbed from the refrigerant coils within the condenser. Another factor in selecting the water level is that the water forced through the feeder flows past all of the inner coils and the topmost ones of the outer coil 27 before its return to the water within the tank lit), and it thereby assumes an elevated temperature which lowers its efliciency in removing heat from the bottom portion of the outer coil 27. Disposing the bottom portion of the outer coil below the water level brings this portion of the coil into contact with water of a lower temperature than that flowing downwardly over the upper portion of the outer coil. The water within the cooling tank 10 is in constant movement by virtue of being recirculated through the condensers by the pump 44. It is not as turbulent, however, as the cooling flow in the vicinity of the inner coil 36 and the upper portion of the outer coil 27. The relatively colder water adjacent the lower portion of the outer coil 27 therefore compensates for the lower degree of turbulence at this location. In the arrangement illustrated, it is evident that the cooling water which has the highest temperature cools the initial portion of the refrigerant coil 27 or 36, while water at the lowest temperature available cools the terminal portion of the inner and outer coils 36 and 27. The lowest temperature water is also present within the feeder 50, thereby to maintain the condensed refrigerant stored within the receiver tank 32 at the lowest possible temperature.

Two additional pumps 56 and 58 are provided which are adapted to pump water from the cooling tank 10 via intake lines 57 and 59, respectively, in a circulating path. The pump 56 forces water to a Water tower 36 (FIG. 5) which may be disposed at some distant location, where the cooling water within the tank 1% is cooled and then returned to the tank on line 6% The operation of the pump is controlled by a thermostat (not shown) disposed within the water in the tank 10, and operates only when the temperature of the water in the cooling tank lit exceeds a predetermined value. The pump 58 is connected to a heating coil 38 (FIG. 5) or the like, also for the purpose of removing heat from the cooling fluid, and returns the flow on line 62 to the tank lit). The pump 58 may be energized in order to make the heat within the cooling fluid available at some desired location, particularly at the winter time. The operation of the pump 53 is controlled by thermostatic means responsive both to the temperature of the water within the cooling tank 10, and to the temperature of the area which is desired to be heated. Such thermostatic controls are well known by those skilled in the art and form no part of the present invention.

The return lines and 62, in the circuits including the pumps 56 and 58, respectively, enter the cooling tank 10 at a remote location from the intake lines 57 and 59, and are directed in such a manner as to promote a swirling within the tank 10. Thus, as illustrated in FIG. 3, the water returning to the tank on lines 6t and 52 promotes a clockwise swirling of the water within the tank 16. This swirling of the water within the cooling tank 10 enhances the turbulence of the water and prevents any isothermal layers from forming within the tank It).

Referring now to FIG. 5, there is illustrated a refrigeration-defrosting system embodying the present invention. The cooling tank 10 is indicated in dashed lines as enclosing a condenser-receiver 64 and a re-evap apparatus 66. The condenser-receiver 64 is used when the apparatus is being operated to refrigerate a refrigeration unit 68, while the re-evap apparatus is used during a defrosting cycle. An additional condenser-receiver 64 is also illustrated within the tank 10 to indicate a plurality of condenser-receivers may be disposed in the same cooling tank. When the apparatus is operated to refrigerate the refrigeration unit, a pair of solenoid valves '70 and 72 are opened to permit refrigerant to flow in one path, while an additional pair of solenoid valves 74 and 76 are closed. Refrigerant is thus permitted to flow from the compressor 80 through the condenser-receiver 64, the solenoid valve 70, and then through an expansion valve 82 to a coil 84 within the refrigeration unit.

The refrigerant evaporates in the unit coil 84, and thereby absorbs heat from the refrigeration unit. The gaseous refrigerant then flows from the unit coil 84 through the solenoid valve 72 and back to the compressor 80.

It will be appreciated that during this time the heat taken from the refrigeration unit 68 is being dissipated in the tank by heating the cooling fluid therein, which is circulated by the pump 44. When the temperature level of the cooling fluid within the tank 10 reaches a predetermined level, one or the other of the pumps 56 and 58 are actuated to cool the water by forcing it through either a water tower 86 or a heating coil 88. The volume of the water within the tank It is such, however, that it can store a considerable quantity of heat without raising its temperature above a predetermined limit which energizes the pumps 56 and 58. Accordingly, when the system is being employed for defrosting, the fluid within the tank 10 stores a quantity of heat which can be drawn on to assist in defrosting the refrigeration unit 68.

During a defrosting operation, the solenoid valves 70 and 72 are closed while the valves 74 and 76 are open. The hot gaseous refrigerant flows from the compressor 80 through the solenoid valve 76 to the unit coil 84, through which it passes in reverse direction and heats the 'coil 84 sufficiently to melt any ice thereon. The return flow of refrigerant is blocked from passing through the condenser-receiver 64 by the solenoid valve 70, and instead passes through the open solenoid valve 74 through the reevap apparatus 66 and back to the compressor 80. The re-evap apparatus 66 comprises a coil disposed within the tank 10, and is preferably attached to one of the side walls of the tank 10, at a position remote from the condenserreceiver associated with that flow. Thus, as illustrated in FIG. 3, the re-evap coils 66, 66' and 66" for the upper, middle and lower condenser-receivers 64, 64' and 64", are disposed adjacent the middle, lower and upper condenser-receivers, respectively. Alternatively the re-evap coils may be disposed on the bottom of the tank 10 surrounding one or more of the three condensers illustrated in FIGS. 2 and 3. The function of the re-evap coil 66 is to warm up the refrigerant returning to the compressor from the unit coil 84, which refrigerant has been cooled down considerably by passage through the unit coil. Thus the refrigerant takes heat from the water within the tank 10 while evaporating within the re-evap apparatus 66, and therefore attains a higher temperature when compressed by passage through the compressor 80. This efficiently permits the defrosting of the unit coil 84 by storing the heat removed from the coil 84 during the refrigeration cycle in the tank 10, and using that same heat to defrost the coil 84 during the defrosting operation.

As has been noted above, a plurality of condensers 64, 64', etc., may be disposed within the tank 10, each with its own compressor with its own re-evap coil. When this is the case, it is convenient to arrange the automatic defrosting cycles of each of the separate units associated with condensers within the same tank 10 at a different time in staggered relationship in order to approach equalization of the temperature of the water within the tank 10 when any of the units are being defrosted. This is accomplished by, for example, operating two of the systems illustrated in the drawings in their refrigeration mode while the third is being operated in its defrosting mode. Thus the condenser-receiver apparatus of the two refrigerating systems furnish a quantity of heat to the cooling fluid within the tank 10 which is available to be used in evaporating the refrigerant returning from the unit being defrosted. This heat exchange is facilitated both by the agitation or turbulence of the water, within the cooling tank 10, and by the disposition of the re-evap coils adjacent the condenser-receiver apparatus of other systems.

The desired defrosting sequence may be accomplished readily by connecting the control terminals of the solenoid valves 70, 72, 74 and 76 in circuit with timing devices, in the manner well known to those skilled in the art.

The foregoing will so fully and completely described the present invention as to permit others skilled in the art, by applying current knowledge, to adapt the same for varying conditions of service without departing from the essential features of novelty thereof which are intended to be defined and secured by the appended claims.

What is claimed is:

1. Refrigeration apparatus comprising a cooling tank for containing a quantity of cooling fluid, a condenser disposed in said cooling tank comprising a refrigerant receiving tank, a cup-shaped member surrounding said receiving tank and having an upwardly opening lip substantially defining a horizontal plane, said lip being open to said cooling tank, first conduit, means for introducing cooling fluid to the bottom of said cup-shaped member between said cup-shaped member and said receiving tank, the exterior surface of said receiving tank and the interior surface of said cup-shaped member defining a second conduit means for conducting said cooling fluid from the bottom of said cup-shaped member upwardly to said lip, whereby said fluid flows past the bottom and sides of said receiving tank, and also flows over the lip of the cup-shaped member and downwardly over its outer surface, and third conduit means for conducting a flow of refrigerant, said third conduit means being disposed within the flow path of said cooling fluid.

2. Apparatus according to claim 1, wherein said conduit means comprises an elongated tube disposed in the form of a helix between the outer surface of said receiving tank and the interior surface of said cup-shaped member.

3. Apparatus according to claim 1, wherein said con duit means comprises an elongated tube disposed in the form of a helix surrounding the outside surface of said cup-shaped member,

4. Apparatus according to claim 1, including means for causing said refrigerant to flow through said conduit means and then into said receiving tank.

5. Apparatus according to claim 1, wherein said conduit means comprises a first coil of tubing disposed between said receiving tank and the inner surface of the cup-shaped member and a second coil of tubing surrounding the outside surface of said cup-shaped member, means for connecting one end of each of said coils to a compressor for said refrigerant and the other end of each of said coils to said receiving tank, whereby compressed refrigerant flows through said first and second coils in parallel, and then into said receiving tank.

6. Apparatus according to claim 5, wherein said receiving tank is provided with opposed openings in the top and bottom walls thereof, and said introducing means comprises a tube extending within said receiving tank be tween said openings for admitting a flow of cooling fluid through said receiving tank to the bottom of said cupshaped member.

7. A condenser comprising a cylindrical plastic baflie member having an unperforated surface, means for causing a cooling fluid to flow over said surface of said plastic bafile member in a direction substantially parallel thereto, and conduit means for conducting a flow of refrigerant in a direction transverse to said cooling flow, said conduit means being disposed in the path of said cooling flow and presenting an obstruction to the even flow of cooling fluid whereby the flow of cooling fluid past the surface of said conduit means is substantially more turbulent than the flow of said fluid past said baffle member, said baffle member being operative to collect a major amount of the foreign matter in said flow of said cooling fluid, and only a minor amount of such foreign matter being collected by said refrigerant conduit.

8. Condenser-receiver apparatus for use in refrigeration systems comprising a cooling tank, a quantity of cooling fluid disposed within said cooling tank, a cup-shaped member dispersed within said cooling tank and partially submerged within said cooling fluid with the lip of said cup-shaped member extending above the level of said fluid, a refrigerant receiving tank disposed within said cup-shaped member and spaced from the interior surface thereof, a refrigerant conduit juxtaposed with a side of said cup-shaped member, one end of said conduit being connected with the interior of said receiving tank and the other end of said conduit being connected to a source of pressurized refrigerant, and means for circulating said quantity of cooling fluid within said cooling tank for producin g a turbulent flow of said cooling fluid over the outer surface of said conduit.

9. Apparatus according to claim 8, wherein said circulating means comprises pump means having an intake disposed within said cooling tank, and conduit means connected from the outlet of said pump means to the space between said cup-shaped member and said receiving tank.

10. Apparatus according to claim 9, wherein said receiving tank and said cup-shaped member are axially symmetric about the same axis, and said refrigerant conduit opens into said space so as to produce an axially symmetric flow between said receiving tank and said cupshaped member.

11. Apparatus according to claim 10, wherein said refrigerant conduit includes a terminal portion opening into said space, said terminal portion being axially symmetric with respect to said axis.

12. Apparatus according to claim 11, wherein said terminal portion passes through said receiving tank, and

opens into said space at the bottom surface of said receiving tank.

13. Refrigeration apparatus comprising a tank containing a quantity of cooling fluid, a condenser disposed in said tank and at least partially submerged in said cooling fluid, cooling means responsive to the temperature of said cooling fluid to keep the temperature of said cooling fluid below a predetermined maximum temperature, an evaporator coil disposed in said tank and submerged in said cooling fluid, means for conducting a first flow of refrigerant from a source of refrigerant through said condenser to a refrigeration unit and back to said source, and means for selectively causing a second flow of refrigerant to flow from said source to a refrigeration unit and then through said evaporator coil to said source, said first and second flows being mutually exclusive,

whereby said quantity of cooling fluid functions as a heat sink for said condenser and as a heat source for said evaporating coil.

14. Apparatus according to claim 13, wherein said condenser comprises conduit means at least partially submerged in said cooling fluid, and means for recirculating said fluid within said tank to create a turbulent flow of said cooling fluid over the outer surface of said conduit.

15. In a refrigeration system comprising a plurality of refrigeration units, a supply of refrigerant for each unit, a compressor for each unit for recirculating said refrigerant through each unit, a, condenser assembly for all of said units comprising a cooling tank containing a quantity of cooling fluid, a plurality of condenser coils disposed within said cooling tank, each of said coils being connected between a compressor and an associated refrigeration unit, a re-evap coil for each of said compressors, each of said re-evap coils being disposed Within said cooling tank adjacent a condenser associated with a different compressor, selectively operable means for connecting one of said re-evap coils in series with its associated compressor and refrigeration unit and bypassing the condenser associated with that compressor, and means for causing a turbulent flow of said cooling fluid to flow past all of said coils.

16. In a refrigeration system comprising a refrigeration unit, a supply of refrigerant, a compressor, and condenser means for interconnecting said compressor with said refrigeration unit, said condenser means comprising an open top tank for containing a quantity of cooling fluid, a condensing coil disposed in said tank at least partially submerged in said cooling fluid and interconnected between said compressor and said refrigeration unit, and selectively operable means for cooling the coolinng fluid within said tank comprising pump means and cooling means interconnected in series between an inlet and an outlet disposed in said tank, said inlet including a conduit projecting asymmetrically into said tank for directing said cooling fluid asymmetrically into said tank to cause a swirling motion of said fluid within said tank References Cited by the Examiner UNITED STATES PATENTS 1,397,621 11/1921 Corbin -111 X 2,127,732 8/1938 Heitman 165-163 X 2,221,530 11/1940 Strang 62-305 X 2,440,146 4/1948 Kramer 62-278 X 2,698,522 1/1955 La Porte 165-134 X 2,911,801 11/1959 Buehler 62-305 2,970,042 1/1961 Lagerwey 165-134 X 3,012,418 12/1961 Hill 62-506 ROBERT A. OLEARY, Primary Examiner. 

1. REFRIGERATION APPARATUS COMPRISING A COOLING TANK FOR CONTAINING A QUANTITY OF COOLING FLUID, A CONDENSER DISPOSED IN SAID COOLING TANK COMPRISING A REFRIGERANT RECEIVING TANK, A CUP-SHAPED MEMBER SURROUNDING SAID RECEIVING TANK AND HAVING AN UPWARDLY OPENING LIP SUBSTANTIALLY DEFINING A HORIZONTAL PLANE, SAID LIP BEING OPEN TO SAID COOLING TANK, FIRST CONDUIT, MEANS FOR INTRODUCING COOLING FLUID TO THE BOTTOM OF SAID CUP-SHAPED MEMBER BETWEEN SAID CUP-SHAPED MEMBER AND SAID RECEIVING TANK, THE EXTERIOR SURFACE OF SAID RECEIVING TANK AND THE INTERIOR SURFACE OF SAID CUP-SHAPED MEMBER DEFINING A SECOND CONDUIT MEANS FOR CONDUCTING SAID COOLING FLUID FROM THE BOTTOM OF SAID CUP-SHAPED MEMBER UPWARDLY TO SAID LIP, WHEREBY SAID FLUID FLOW PAST THE BOTTOM AND SIDES OF SAID RECEIVING TANK, AND ALSO FLOWS OVER THE LIP OF THE CUP-SHAPED MEMBER AND DOWNWARDLY OVER ITS OUTER SURFACE, AND THIRD CONDUIT MEANS FOR CONDUCTING A FLOW OF REFRIGERANT, SAID THIRD CONDUIT MEANS BEING DISPOSED WITHIN THE FLOW PATH OF SAID COOLING FLUID. 